Thomas a



(No Model.)

T. A. EDISON.

MANUFACTURING CARBONS FOR E'LBOTRIO LIGHTS.

No. 248,417. Patented Oct. 18,1881.

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UNITED. STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, ASSIGNOR TO THE EDISONELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

MANUFACTURING CARBONS FOR ELECTRIC LIGHTS.

SPECIFICATION forming part of Letters Patent No. 248,417, dated October18, 1881. Application filed June 30, 1880. (No model.)

To all whom it may concern Be it known that I, THOMAS A. EDIsoN, ofMenlo Park, in the county of Middlesex and State of NewJersey, haveinvented a new and useful Method of Manufacturing Oarbons for ElectricLamps; and I do hereby declare that the following is a full and exactdescription of the same, reference being had to the accompanyingdrawings, and to the letters of reference marked thereon.

This invention relates to the manufacture of carbons from wood forincandescing conductors in electric lamps.

As explained in previous applications by me made for patents forinventions relating to the same subject-matter, an incandescingconductoris needed which shall be exceedingly smallin fact, a mere filament inthe light-givingportionbut with ends somewhat enlarged, so as to aflorda good connection for the clamps which are to support the carbons andconnect them to the conductors. These incandescing conductors are madeas part of an oval, and are ordinarilydesignated horseshoe carbons.

In the present invention a block of wood is' taken and cut in a machineor lathe for turning irregular forms until its shape is that of anelongated oval, of which about one-third, including an end, is out uponsomewhat larger axes than the remainder, in order to provide for theclamps. The interior is then reamed out in a suitable machine, so thatthe block then resembles a series of carbon horseshoes with closed endspiled upon each other. The length of the ovalis with the grain ofthewood. The block is then split or sawed into very thin layers or slips,each forming ultimately one horseshoe carbon. The slips are thencarbonized, preferably in a nickel flask ofa description shown in aprior application. After carbonization the greater portion of thebroader end of the slip is cutoff, leaving the horseshoe in shape foruse. This broader end, which connects what are afterward the ends of thehorseshoe, may, if desired, be out ofl'prior to carbonization; but asthis broader connecting end tends to support and keep in shape theportion s afterward forming the horseshoe, it is better to leave it onuntil after carbonization. Eitherbeforeoraftercarbonization,(preferablybefore,) and before the slips are sawed or split. from the block, smallholes are made in the broad end, through which pass the clampscrews.

In the drawings, Figure l is a perspective view of the block partiallyturned in proper shape. Fig. 2 is a front view ofa carbon aftercarbonization. Fig. 3 is aside view of a carbo properly secured inclamps.

A is a block of wood, which, in a proper ma- 6o chine, is turned so thatits exterior shape is that of an oval, composed oftwo ovals, B O, ofdifferent axes, thereby forming a broadened portion for the clamps, theinterior being reamed out to present a uniform smooth surface, F. Thisblock, so shaped, is then split or sawed into very thin layers or slipsof a thickness sufficientforone carbon horseshoe,as seen in Figs. 2 and3. These slips are then carbonized and a portion of 0 broken or out offat 0 7o 0, as shown in dotted lines in Fig. 2.

Atsome stage in the process, preferably while in the shape shown inFig.1, holes 61 d are drilled for the reception of the screws 0, whichfasten the clamps D tothe carbon.

What I claim is- The method of forming carbons for the incandescingconductors oi'electriolights, consisting in cutting or turning a blockof Wood into the shape of an oval having a broadened portion and reamingout the central portion of such oval, then slicing the block intolayers, and then carbonizing the layers, a portion of the broadened partbeing removed before or after carbonizaiion, substantially as set forth.

This specification signed and witnessed this 15th day of June, 1880.

THOS. A. EDISON.

Witnesses S. L. GRIFFIN, WM. OARMAN.

